Fungi 2; Slime molds

Reproduction; Fungal divisions

Dr. Clem Kuek ZIP\Lectures\Basic\Lectures\Fungi\Fungi2\Fungi2.ppt

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Reproduction

Asexual sporulation

Mitosis and cell division to form several types of asexual spores •

Arthroconidia or arthrospores

Cells fragmented by formation of new septa. New cells function as spores.

•

Chlamydospores

Cells surrounded by thick walls before separation.

•

Sporangiospores

Spores developed within a sac (sporangium).

•

Conidiospores

Not in sac but on tips or sides of hypha.

•

Blastospores

Produced from mother cells by budding.

Dr. Clem Kuek ZIP\Lectures\Basic\Lectures\Fungi\Fungi2\Fungi2.ppt

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Reproduction

Sexual sporulation

• Meiosis and fusion; spores genetically different from mother cells.

• Specialized hyphal structures form fruiting bodies which produce spores.

Three stages of sexual reproduction:

1. Donor (+) haploid nucleus penetrates cytoplasm of recipient cell (-).

2. (+) and (-) nuclei fuse  diploid zygote.

3. Diploid nucleus gives rise to haploid spores via meiosis (some spores may be genetic recombinants).

• Fruiting body and spore structures vary with phyla.

• Spores distributed by wind, water and vectors.

Dr. Clem Kuek ZIP\Lectures\Basic\Lectures\Fungi\Fungi2\Fungi2.ppt

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Reproduction

Dr. Clem Kuek The asexual life cycle of

Rhizopus

, a zygomycete Tortora

et al

., 2001; Fig. 12. 6 ZIP\Lectures\Basic\Lectures\Fungi\Fungi2\Fungi2.ppt

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Reproduction

Dr. Clem Kuek The sexual life cycle of

Rhizopus

, a zygomycete Tortora

et al.,

2001; Fig. 12. 6 ZIP\Lectures\Basic\Lectures\Fungi\Fungi2\Fungi2.ppt

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Reproduction

Dr. Clem Kuek The life cycle of

Eupenicllium

, an ascomycete Tortora

et al

., 2001; Fig. 12.7 ) ZIP\Lectures\Basic\Lectures\Fungi\Fungi2\Fungi2.ppt

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Reproduction

Dr. Clem Kuek A generalized life cycle of a basidiomycete Tortora

et al.

, 2001; Fig. 12.8 ZIP\Lectures\Basic\Lectures\Fungi\Fungi2\Fungi2.ppt

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Characteristics of the fungal divisions

• Four major phyla of fungi.

• Classification based primarily on variations in production of sexual spores.

Characteristics of Fungal Phyla Hyphae Propagation

Zygomycota Ascomycota Deuteromycota Basidiomycota Dr. Clem Kuek aseptate septate septate septate sexual sporulation sexual sporulation asexual sporulation hyphal structures sexual sporulation asexual sporulation ZIP\Lectures\Basic\Lectures\Fungi\Fungi2\Fungi2.ppt

Approx. No. of Species

600 35,000 30,000 30,000 8

Characteristics of the fungal divisions

Division Zygomycota

• Known as the conjugation fungi.

• Asexual spores: sporangium (

pl.

–gia).

• Sexual spores: thick-walled resting spores (zygospores) • Example:

Rhizopus stolonifer

Dr. Clem Kuek ZIP\Lectures\Basic\Lectures\Fungi\Fungi2\Fungi2.ppt

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Characteristics of the fungal divisions

Division Ascomycota

• Known as the sac fungi after the sac-like

ascus

which spores are borne.

(

pl.

asci) in • Many red, brown and blue-green spoilage fungi belong to this division • Many are parasites on higher plants

e.g. Claviceps purpurea

(ergot of cereals).

Dr. Clem Kuek ZIP\Lectures\Basic\Lectures\Fungi\Fungi2\Fungi2.ppt

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Characteristics of the fungal divisions

Division Basidiomycota

• Known as the club fungi after the club-shaped

basidium

involved in sexual reproduction. Spores borne externally on the basidium.

• Most are saprophytes.

•

Crytococcus neoformans

is an important human pathogen (crytococcosis – lung infection).

• Many mushrooms used as foods

e.g. Agaricus campestris, Lentinus edodes, Pleurotus

sp.

Dr. Clem Kuek ZIP\Lectures\Basic\Lectures\Fungi\Fungi2\Fungi2.ppt

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Characteristics of the fungal divisions

Division Deuteromycota

• Fungi without a known sexual reproductive stage. Therefore, limited to chlamydospores, arthrospores, conidiospores and budding.

• Also known as the Fungi Imperfecti; a “holding category”.

• Saprophytes and parasites (

e.g.

in athelete’s foot and ringworm); most terrestrial.

• Important in industry

e.g. Penicillium

(antibiotics; cheese making),

Aspergillus

sp. (enzymes).

Dr. Clem Kuek ZIP\Lectures\Basic\Lectures\Fungi\Fungi2\Fungi2.ppt

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Characteristics of the fungal divisions

Division Chytridiomycota

• Simplest of the true fungi • Terrestrial and aquatic.

• Motile sexual and asexual spores.

Asexual reproduction: motile zoospores Sexual reproduction: Zygote.

Dr. Clem Kuek ZIP\Lectures\Basic\Lectures\Fungi\Fungi2\Fungi2.ppt

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Slime Molds

Have both fungal and animal characteristics; therefore are protists.

Division Myxomycota (plasmodial slime molds)

• Streaming masses of colorful protoplasm (plasmodium – no cell walls).

• Feeding is by phagocytosis.

• Reproduction.

 When mature (or under unfavorable conditions), ornate fruting bodies are developed.  Spores germinate to form either myxamoebae (non-flagellated) or flagellated swarm cells (both haploid).  The latter and former fuse to form zygotes which grows into the multinucleate plasmodium.

14 Dr. Clem Kuek ZIP\Lectures\Basic\Lectures\Fungi\Fungi2\Fungi2.ppt

Slime Molds

Dr. Clem Kuek ZIP\Lectures\Basic\Lectures\Fungi\Fungi2\Fungi2.ppt

Totora

et al.,

2001; Fig.12.22

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Slime Molds

Division Acrasiomycota (cellular slime molds)

Dr. Clem Kuek ZIP\Lectures\Basic\Lectures\Fungi\Fungi2\Fungi2.ppt

Totora

et al.,

2001; Fig.12.21

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